Seroprevalence of anti‐SARS‐CoV‐2 antibodies in COVID‐19 patients and healthy volunteers up to 6 months post disease onset

  1. Patrícia Figueiredo‐Campos
  2. Birte Blankenhaus
  3. Catarina Mota
  4. Andreia Gomes
  5. Marta Serrano
  6. Silvia Ariotti
  7. Catarina Costa
  8. Helena Nunes‐Cabaço
  9. António M. Mendes
  10. Pedro Gaspar
  11. M. Conceição Pereira‐Santos
  12. Fabiana Rodrigues
  13. Jorge Condeço
  14. M. Antonia Escoval
  15. Matilde Santos
  16. Mario Ramirez
  17. José Melo‐Cristino
  18. J. Pedro Simas
  19. Eugenia Vasconcelos
  20. Ângela Afonso
  21. Marc Veldhoen

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Abstract

SARS‐CoV‐2 has emerged as a human pathogen, causing clinical signs, from fever to pneumonia—COVID‐19—but may remain mild or asymptomatic. To understand the continuing spread of the virus, to detect those who are and were infected, and to follow the immune response longitudinally, reliable and robust assays for SARS‐CoV‐2 detection and immunological monitoring are needed. We quantified IgM, IgG, and IgA antibodies recognizing the SARS‐CoV‐2 receptor‐binding domain (RBD) or the Spike (S) protein over a period of 6 months following COVID‐19 onset. We report the detailed setup to monitor the humoral immune response from over 300 COVID‐19 hospital patients and healthcare workers, 2500 University staff, and 198 post‐COVID‐19 volunteers. Anti‐SARS‐CoV‐2 antibody responses follow a classic pattern with a rapid increase within the first three weeks after symptoms. Although titres reduce subsequently, the ability to detect anti‐SARS‐CoV‐2 IgG antibodies remained robust with confirmed neutralization activity for up to 6 months in a large proportion of previously virus‐positive screened subjects. Our work provides detailed information for the assays used, facilitating further and longitudinal analysis of protective immunity to SARS‐CoV‐2. Importantly, it highlights a continued level of circulating neutralising antibodies in most people with confirmed SARS‐CoV‐2.

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  1. ScreenIT

    SciScore for 10.1101/2020.08.30.20184309: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementConsent: Human samples collection: Upon informed consent, blood was taken by vein puncture and two BD Vacutainer CPT tubes of blood and one serum tube were collected per patient.
    IRB: The COVID-19 collection and scientific use was approved by the Lisbon Academic Medical Center Ethics Committee (Ref. n.° 155/20) as was the staff screening (Ref. n.° 181/20).
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Antibody measurements: Anti-SARS-CoV-2 ELISAs were performed as described previously [12].
    Anti-SARS-CoV-2
    suggested: None
    Serum samples were diluted in PBS-0.1%T + 1% non-fat milk powder, added (100 μl/well) and incubated for 1-2 hours at room temperature, washed with PBS-T 3x or 10x Hereafter several antibody isotypes, namely Total Ig, IgG, IgM and IgA anti-SARS-CoV2 were detected using horseradish peroxidase (HRP)-labelled goat anti-human IgG+IgM+IgA (Abcam, ab102420)
    anti-SARS-CoV2
    suggested: None
    anti-human IgG+IgM+IgA
    suggested: (Meridian Life Science Cat# W99549G, RRID:AB_152010)
    Experimental Models: Cell Lines
    SentencesResources
    Briefly, 24 hours prior to infection, Vero CCL81 cells grown in DMEM supplemented with 10% FBS were seeded at 20,000 per well in a 96-well plate.
    Vero CCL81
    suggested: None
    Media from Vero cells was substituted with the SARS-CoV-2pp/serum mix; plates were spinoculated by centrifugation at 1250rpm for 1 hr at 37°C.
    Vero
    suggested: None
    Software and Algorithms
    SentencesResources
    Statistical analyses: A Kruskal-Wallis test (non-parametric test) was done to compare the geometric ratios between groups with a significance level of 0.05 (Dunn’s multiple comparisons test), student t test or two-way ANOVA were used as stated in the figure legends, calculated using GraphPad Prism 6.0 software.
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  2. Version published to 10.1002/eji.202048970
  3. Version published to 10.1101/2020.08.30.20184309v1 on medRxiv